US 7274329 B2 Abstract A method and apparatus for correcting a beam error is disclosed. One embodiment of the method comprises the steps of selecting beamweight coefficients based on the satellite orbital data, evaluating an effect of quantization of the beamweight coefficients on the beam error, and selecting beamweight coefficients based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error. One embodiment of the apparatus comprises a beamweight correction module for selecting beamweight coefficients based on satellite orbital data, for evaluating the effect of quantization of the beamweight coefficients on beam error, and for selecting beamweight coefficients based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error. The beamweight correction module comprises a beamweight generator and a beamweight quantizer for quantizing beamweights from the beamweight generator.
Claims(60) 1. A method of correcting for beam error, comprising the steps of:
selecting first beamweight coefficients based on the satellite orbital data;
evaluating an effect of quantization of the first beamweight coefficients on the beam error; and
selecting second beamweight coefficients that correct for the beam error, the second beamweight coefficients selection based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error.
2. The method of
3. The method of
selecting nominal beamweight coefficients from the first beamweight coefficients, wherein at least one of the nominal beamweight coefficients is a nominal sensitive beamweight coefficient such that changes in the nominal sensitive beamweight coefficient results in changes to the beam exceeding changes to the beam resulting from changes in at least one of the nominal other beamweight coefficients;
generating quantized nominal beamweight coefficients including a quantized nominal sensitive beamweight coefficient and quantized nominal other beamweight coefficients;
quantizing perturbed sensitive beamweight coefficients; and
comparing a first beam pattern calculated from the quantized nominal sensitive beamweight coefficients to a second beam pattern calculated from the quantized perturbed sensitive beamweight coefficients and a third beam pattern calculated form the nominal sensitive beamweight coefficients.
4. The method of
selecting the nominal beamweight coefficients if the first beam pattern calculated from the quantized nominal sensitive beamweight coefficients is closer to the third beam pattern calculated from the nominal sensitive beamweight coefficients than the second beam pattern calculated from the perturbed sensitive beamweight coefficients; and
selecting perturbed beamweight coefficients if the first beam pattern calculated from the quantized nominal sensitive beamweight coefficients is closer to the second beam pattern calculated from the perturbed sensitive beamweight coefficients than the third beam pattern calculated from nominal sensitive beamweight coefficients.
5. The method of
the perturbed beamweight coefficients are computed by setting the nominal sensitive beamweight coefficient to a perturbed value and computing remaining perturbed beamweight coefficients.
6. The method of
the perturbed value is a fraction of the quantization.
7. The method of
generating the normal beamweight coefficients and the perturbed beamweight coefficients from the satellite orbit data.
8. The method of
segmenting the first nominal beamweight coefficients into at least one nominal sensitive beamweight coefficient and other nominal beamweight coefficients, wherein changes in the nominal sensitive beamweight coefficient result in changes to the beam exceeding changes to the beam resulting from changes in at least one of the other nominal beamweight coefficients;
generating a first tile comprising a first beamweight coefficient set by setting the nominal sensitive beamweight coefficient and computing the other nominal beamweight coefficients; and
generating a second tile comprising a second beamweight coefficient set by setting the nominal sensitive beamweight coefficient to a perturbed sensitive beamweight coefficient and computing the remaining beamweight coefficients.
9. The method of
the perturbed sensitive beamweight coefficient is a fraction of a beamweight quantization error.
10. The method of
quantizing the nominal sensitive beamweight coefficient and the calculated other nominal beamweight coefficients from the first tile; and
comparing the quantized nominal sensitive beamweight coefficient to the perturbed sensitive beamweight coefficient and the nominal sensitive beamweight coefficient.
11. The method of
selecting the first tile of beamweight coefficients if the quantized nominal sensitive beamweight coefficient is closer to the nominal sensitive beamweight coefficient than the perturbed sensitive beamweight coefficient; and
selecting the second file of beamweight coefficients if the quantized nominal sensitive beamweight coefficient is closer to the perturbed sensitive beamweight coefficient than the nominal sensitive beamweight coefficient.
12. The method of
generating a set of nominal beamweight coefficients for a nominal beam from the first beamweight coefficients;
quantizing the nominal beamweight coefficients;
computing a nominal beam value for the set of quantized nominal beamweight coefficients;
generating a set of perturbed beamweight coefficients for a perturbed beam from the first beamweight coefficients, the perturbed beam angularly displaced from the nominal beam by an amount approximating an angular shift induced by quantization;
quantizing the perturbed beamweight coefficients;
computing a perturbed beam value from the quantized, perturbed beamweight coefficients; and
comparing the nominal beam value and the perturbed beam value.
13. The method of
the nominal beam value includes an effective isotropic radiated power (EIRP) of a vertex of the nominal beam; and
the perturbed beam value includes an EIRP of the perturbed beam at the vertex of the nominal beam.
14. The method of
selecting the set of nominal beamweight coefficients if the nominal beam value exceeds the perturbed beam value; and
selecting the set of perturbed beamweight coefficients if the perturbed beam value exceeds the nominal beam value.
15. The method of
16. The method of
computing an antenna pattern from the quantized set of nominal beamweight coefficients; and
computing a beam EIRP at each of the nominal beam vertices from the antenna pattern.
17. The method of
computing an antenna pattern from the quantized set of perturbed beamweight coefficients; and
computing a beam EIRP at each of the nominal beam vertices from the antenna pattern.
18. The method of
generating a set of nominal beamweight coefficients for a nominal beam from the first beamweight coefficients, the nominal beam having N nominal beam vertices;
quantizing the nominal beamweight coefficients;
computing a nominal beam value at each of the nominal beam vertices for the quantized nominal beamweight coefficients;
generating a set of perturbed beamweight coefficients for each of N perturbed beams from the first beamweight coefficients, each perturbed beam angularly displaced from the nominal beam by an amount approximating an angular shift induced by quantization and in a direction of one of the N nominal beam vertices;
selecting one of the perturbed beams adjacent die selected nominal beam vertex;
quantizing the set of perturbed beamweight coefficients for the selected perturbed beam;
computing a perturbed beam value at each of the nominal beam vertices for the quantized set of perturbed beamweight coefficients;
comparing the nominal beam values and the perturbed beam values at at least a portion of the vertices; and
selecting the nominal beamweight coefficients according to the comparison between the nominal beam values and the perturbed beam values at at least a portion of the vertices.
19. The method of
selecting the nominal beamweight coefficients if a combination of the perturbed beam values at each of the nominal beam vertices does not exceed a combination of the nominal beam values at each of the nominal beam vertices; and
selecting the perturbed beamweight coefficients if the combination of the perturbed beam values at each of the nominal beam vertices exceeds the combination of the nominal beam values at each of the nominal beam vertices.
20. The method of
selecting the nominal beamweight coefficients if a lowest perturbed beam value at each of the nominal beam vertices does not exceed the lowest nominal beam value at each of the nominal beam vertices; and
selecting the perturbed beamweight coefficients if the lowest perturbed beam value at each of the nominal beam vertices exceeds the lowest nominal beam value at each of the nominal beam vertices.
21. An apparatus for correcting for beam error, comprising:
means for selecting first beamweight coefficients based on the satellite orbital data;
means for evaluating an effect of quantization of the first beamweight coefficients on the beam error; and
means for selecting second beamweight coefficients that correct for the beam error, the second beamweight coefficients selection based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error.
22. The apparatus of
23. The apparatus of
means for selecting nominal beamweight coefficients from the first beamweight coefficients, wherein at least one of the nominal beamweight coefficients is a nominal sensitive beamweight coefficient such that changes in the nominal sensitive beamweight coefficient results in changes to the beam exceeding changes to the beam resulting from changes in at least one of the nominal other beamweight coefficients;
means for generating quantized nominal beamweight coefficients including a quantized nominal sensitive beamweight coefficient and quantized nominal other beamweight coefficients;
means for quantizing perturbed sensitive beamweight coefficients; and
means for comparing a first beam pattern calculated from the quantized nominal sensitive beamweight coefficients to a second beam calculated from the quantized perturbed sensitive beamweight coefficients and a third beam pattern calculated from the nominal sensitive beamweight coefficients.
24. The apparatus of
means for selecting the nominal beamweight coefficients if the first beam pattern calculated from the quantized nominal sensitive beamweight coefficients is closer to the third beam pattern calculated from the nominal sensitive beamweight coefficients than the second beam pattern calculated from the perturbed sensitive beamweight coefficients; and
means for selecting perturbed beamweight coefficients if the first beam pattern calculated from the quantized nominal sensitive beamweight coefficients is closer to the second beam pattern calculated from the perturbed sensitive beamweight coefficients than the third beam pattern calculated from the nominal sensitive beamweight coefficients.
25. The apparatus of
the perturbed beamweight coefficients are computed by setting the nominal sensitive beamweight coefficient to a perturbed value and computing remaining perturbed beamweight coefficients.
26. The apparatus of
the perturbed value is a fraction of the quantization.
27. The apparatus of
means for generating the normal beamweight coefficients and the perturbed beamweight coefficients from the satellite orbit data.
28. The apparatus of
means for segmenting the first nominal beamweight coefficients into at least one nominal sensitive beamweight coefficient and other nominal beamweight coefficients, wherein changes in the nominal sensitive beamweight coefficient result in changes to the beam exceeding changes to the ben resulting from changes in at least one of the other nominal beamweight coefficients;
means for generating a first tile comprising a first beamweight coefficient set by setting the nominal sensitive beamweight coefficient to a nominal sensitive beamweight coefficient value and computing the other nominal beamweight coefficients; and
means for generating a second tile comprising a second beamweight coefficient set by setting the nominal sensitive beamweight coefficient to a perturbed sensitive beamweight coefficient value and computing the remaining beamweight coefficients.
29. The apparatus of
the perturbed sensitive beamweight coefficient value is a fraction of a beamweight quantization error.
30. The apparatus of
means for quantizing die nominal sensitive beamweight coefficient and the calculated other nominal beamweight coefficients from the first tile; and
comparing the quantized nominal sensitive beamweight coefficient to the perturbed sensitive beamweight coefficient and the nominal sensitive beamweight coefficient.
31. The apparatus of
means for selecting the first tile of beamweight coefficients if the quantized nominal sensitive beamweight coefficient is closer to the nominal sensitive beamweight coefficient than the perturbed sensitive beamweight coefficient; and
means for selecting the second tile of beamweight coefficients if the quantized nominal sensitive beamweight coefficient is closer to the perturbed sensitive beamweight coefficient than the nominal sensitive beamweight coefficient.
32. The apparatus of
means for generating a set of nominal beamweight coefficients for a nominal beam from the first beamweight coefficients;
means for quantizing the nominal beamweight coefficients;
means for computing a nominal beam value for the set of nominal beamweight coefficients;
means for generating a set of perturbed beamweight coefficients for a perturbed beam from the first beamweight coefficients, the perturbed beam angularly displaced from the nominal beam by an amount approximating an angular shift induced by quantization;
means for quantizing the perturbed beamweight coefficients;
means for computing a perturbed beam value from the quantized, perturbed beamweight coefficients; and
means for comparing the nominal beam value and the perturbed beam value.
33. The apparatus of
the nominal beam value includes an effective isotropic radiated power (EIRP) of a vertex of the nominal beam; and
the perturbed beam value includes an EIRP of the perturbed beans at the vertex of the nominal beam.
34. The apparatus of
means for selecting the set of nominal beamweight coefficients if the nominal beam value exceeds the perturbed beam value; and
means for selecting the set of perturbed beamweight coefficients if the perturbed beam value exceeds the nominal beam value.
35. The apparatus of
36. The apparatus of
means for computing an antenna pattern from the quantized set of nominal beamweight coefficients; and
means for computing a beam EIRP at each of the nominal beam vertices from the antenna pattern.
37. The apparatus of
means for computing an antenna pattern from the quantized set of perturbed beamweight coefficients; and
means for computing a beam EIRP at each of the nominal beam vertices from the antenna pattern.
38. The apparatus of
means for generating a set of nominal beamweight coefficients for a nominal beam from the first beamweight coefficients, the nominal beam having N of nominal beam vertices;
means for quantizing the nominal beamweight coefficients;
means for generating a set of perturbed beamweight coefficients for each of N perturbed beams from the first beamweight coefficients, each perturbed beam angularly displaced from the nominal beam by an amount approximating an angular shift induced by quantization and in a direction of one of the N nominal beam vertices;
means for computing a nominal beam value at each of the nominal beam vertices for the quantized nominal beamweight coefficients;
means for selecting one of the perturbed beams adjacent the selected nominal beam vertex;
means for quantizing the set of perturbed beamweight coefficients for the selected perturbed beam;
means for computing a perturbed beam value at each of the nominal beam vertices for the quantized set of perturbed beamweight coefficients;
means for comparing the nominal beam values and the perturbed beam values at at least a portion of the vertices; and
means for selecting the nominal beamweight coefficients according to the comparison between the nominal beam values and the perturbed beam values at at least a portion of the vertices.
39. The apparatus of
means for selecting the nominal beamweight coefficients if a combination of the perturbed beam values at each of the nominal beam vertices does not exceed a combination of the nominal beam values at each of the nominal beam vertices; and
means for selecting the perturbed beamweight coefficients if the combination of the perturbed beam values at each of the nominal beam vertices exceeds the combination of the nominal beam values at each of the nominal beam vertices.
40. The apparatus of
means for selecting the nominal beamweight coefficients if a lowest perturbed beam value at each of the nominal beam vertices does not exceed the lowest nominal beam value at each of the nominal beam vertices; and
means for selecting the perturbed beamweight coefficients if the lowest perturbed beam value at each of the nominal beam vertices exceeds the lowest nominal beam value at each of the nominal beam vertices.
41. An apparatus for correcting for beam error, comprising:
a beamweight correction module for selecting first beamweight coefficients based on satellite orbital data, for evaluating the effect of quantization of the first beamweight coefficients on beam error, and for selecting second beamweight coefficients that correct for the beam error, the second beamweight coefficient selection based at least in part upon the evaluation of the effect of beamweight coefficient quantization on beam error, the beamweight correction module comprising
a beamweight generator; and
a beamweight quantizer for quantizing beamweights from the beamweight generator.
42. The apparatus of
43. The apparatus of
44. The apparatus of
45. The apparatus of
46. The apparatus of
the beamweight correction module further selects nominal beamweight coefficients from the first beamweight coefficients, wherein at least one of the nominal beamweight coefficients is a nominal sensitive beamweight coefficient such that changes in the nominal sensitive beamweight coefficient results in changes to the beam exceeding changes to the beam resulting from changes in at least one of the nominal other beamweight coefficients;
the beamweight quantizer generates quantized nominal beamweight coefficients including a quantized nominal sensitive beamweight coefficient and quantized nominal other beamweight coefficients;
the beamweight quantizer quantizes perturbed sensitive beamweight coefficients; and
the beamweight correction module compares a first beam pattern calculated from the quantized nominal sensitive beamweight coefficients to a second beam pattern calculated from the quantized perturbed sensitive beamweight coefficients and a third beam pattern calculated from the nominal sensitive beamweight coefficients.
47. The apparatus of
48. The apparatus of
the perturbed beamweight coefficients are computed by setting the nominal sensitive beamweight coefficient to a perturbed value and computing other perturbed beamweight coefficients.
49. The apparatus of
the perturbed value is a fraction of the quantization.
50. The apparatus of
51. The apparatus of
segments the first nominal beamweight coefficients into at least one nominal sensitive beamweight coefficient and other nominal beamweight coefficients, wherein changes in the nominal sensitive beamweight coefficient result in changes to the beam exceeding changes to the beam resulting from changes in at least one of the other nominal beamweight coefficients;
generates a first tile comprising a first beamweight coefficient set by setting the nominal sensitive beamweight coefficient and computing the other nominal beamweight coefficients; and
generates a second tile comprising a second beamweight coefficient set by setting the nominal sensitive beamweight coefficient to a perturbed sensitive beamweight coefficient and computing the remaining beamweight coefficients.
52. The apparatus of
the perturbed sensitive beamweight coefficient is a fraction of a beamweight quantization error.
53. The apparatus of
54. The apparatus of
55. The apparatus of
the beamweight correction module generates a set of nominal beamweight coefficients for a nominal beam from the first beamweight coefficients;
the beamweight quantizer quantizes the nominal beamweight coefficients;
the beamweight correction module further comprises an antenna pattern calculator for computing a nominal beam value for the set of nominal beamweight coefficients;
the beamweight correction module generates a set of perturbed beamweight coefficients for a perturbed beam from the first beamweight coefficients, the perturbed beam angularly displaced from the nominal beam by an amount approximating an angular shift induced by quantization;
the beamweight quantizer quantizes the perturbed beamweight coefficients;
the antenna pattern calculator computes a perturbed beam value from the quantized, perturbed beamweight coefficients; and
the beamweight correction module compares the nominal beam value and the perturbed beam value.
56. The apparatus of
the nominal beam value includes an effective isotropic radiated power (EIRP) of a vertex of the nominal beam; and
the perturbed beam value includes an EIRP of the perturbed beam at the vertex of the nominal beam.
57. The apparatus of
58. The apparatus of
59. The apparatus of
60. The apparatus of
Description This application claims benefit of U.S. Provisional Patent Application No. 60/486,625, entitled “MITIGATION OF BEAM-FORMING ERRORS DUE TO GAIN/PHASE SHIFTS AND QUANTIZATION,” by Richard A. Fowell and Hanching G. Wang, filed Jul. 11, 2003, which application is hereby incorporated by reference herein. This application is also related to the following co-pending and commonly assigned patent application(s), all of which applications are incorporated by reference herein: Application Ser. No. 10/877,564, “entitled METHOD AND APPARATUS FOR CORRECTION OF QUANTIZATION-INDUCED BEACON BEAM ERRORS,” filed on Jun. 25, 2004, by Richard A. Fowell and Hanching G. Wang; and Application Ser. No. 10/877,423, entitled “METHOD AND APPARATUS FOR PREDICTION AND CORRECTION OF GAIN AND PHASE ERRORS IN A BEACON OR PAYLOAD”, filed Jun. 25, 2004, by Richard A. Fowell and Hanching G. Wang. 1. Field of the Invention The present invention relates to systems and methods for satellite navigation, and in particular to a system and method for reducing error from beacon measurements used for satellite navigation, and for reducing payload pointing error. 2. Description of the Related Art Spacecraft typically have one or more payloads that are directed to transmit or receive energy from ground stations. For example, communication satellites include one or more uplink antennas for receiving information from an uplink center, and one or more downlink antennas for transmitting and/or receiving (transceiving) information with terrestrial transceivers. The uplink and downlink antennas are typically disposed on the satellite body (or spacecraft bus) and are directed toward a terrestrial location where an uplink/downlink antenna is transmitting/receiving the information. In many cases, the information is beamed to and/or received from a plurality of terrestrial receivers spanning a wide geographical area. In such situations, the pointing accuracy of the uplink/downlink antennas are not particularly critical. However, in other cases, spacecraft payloads must be pointed at the desired target with a high degree of accuracy. This can be the case, for example, in cases where the uplink/downlink antenna is a narrow beamwidth antenna, or when spatial diversity is critical. In such situations, a spacecraft's on-board navigation system (which relies on inertial sensors and perhaps Sun, Earth, Moon, star, and magnetic sensors as well) often cannot support the precise pointing requirement. In such cases, beacon sensor systems can be used to increase payload pointing performance and spacecraft body attitude accuracy. The beacon sensor system monitors an uplink carrier (which can also be used to provide commands to the satellite) to sense mispointing of the antenna structure. Using the beacon sensor data as a reference, the satellite navigational system parameters can be updated to improve accuracy. The beacon sensor data can be used to replace other sensor data. Recent technology advances include the use of digital beacons. In a digital beacon, the beacon beams are formed digitally using an on-board Digital Signal Processor (DSP). The beacon beams are formed by selecting desired beam weights for each feed chain. However, the accuracy of the digital beacon system is negatively affected by the performance limitations of the digital beam-forming technique and its implementation. Although some digital beacon sensor errors can be ameliorated by calibration and the adjustment of weighting to beacon sensor channels (beamweights), asymmetry errors due to beam-forming approximation by finite number of feed chains, quantization errors due to the finite-bit representation of the weighting factors themselves, and errors in the gain and phase calibration of each of the beacon sensor channels can severely impact beacon accuracy and therefore payload pointing accuracy. What is needed is a system and method for compensating for such asymmetry error and quantization errors. The present invention satisfies this need. To address the requirements described above, the present invention discloses a method and apparatus for correcting for beacon pointing errors. In one embodiment, the method comprises the steps of computing a desired beacon value, computing a predicted measured beacon value, and generating a beacon correction at least in part from the desired beacon value and the predicted measured beacon value. In another embodiment, the invention is expressed as an apparatus comprising an antenna pattern calculator, for computing a predicted measured beacon value, and a beacon correction value generator, for computing a desired beacon value, and for generating a beacon correction at least in part from the desired beacon value and the predicted measured beacon beam value. Referring now to the drawings in which like reference numbers represent corresponding parts throughout: In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments of the present invention. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. The three axes of the spacecraft Input to the spacecraft control processor The SCP The SCP Generally, the spacecraft Wheel torque commands When momentum wheel assemblies are used, the spacecraft control processor also sends jackscrew drive signals For some satellites, the spacecraft control processor The SCP The SCP The SCP In one embodiment, instructions implementing the operating system The antenna Typically, the beacon sensor The beacon tracking system The output of each feed The downconverted IF signal is then provided to a digital signal processor (DSP) The beacon null correction values In current systems, beacon correction values Beacon beamweights The continuous beacon beamweights In the current designs, the calculations of the adjustments to the elements Beam errors can be reduced through one or more of the following techniques, which can be used alone or in combination and are discussed in further detail below: 1. Adjust on-board satellite 2. Reduce the quantization errors by selecting the quantized coefficients based in part on an evaluation of the effects of the quantization on beam quality; 3. Using data beyond channel element gain/phase measurements taken since the latest beamweight coefficients update to produce gain/phase element estimates, and use those estimates to compute the next coefficient element update for that element chain. These estimates can be based on more complex means than simple equal weighted averaging and/or first order filtering of the available data, and can be specifically optimized to cover the period between the next update, and the following update. One of the significant errors in the beacon pointing is the change in the beacon beam While quantization errors effect all the communication beams, not just those used to form the pointing beacon, errors in the beacon beams are especially pernicious. While quantization errors in the weights of a particular communication beam affect the pointing of that beam alone, quantization errors in the pointing beacon beams result in an erroneous correction by the satellite attitude control system which will follow that error and drag the several hundreds of payload beams with it, affecting the pointing of all the beams. Fortunately, the effect of the quantization errors on the beam shape are predictable . . . that is, given the quantized beamweight coefficients and the calibrated element chain (e.g. Over the period between the upcoming beacon beam coefficient update and the next, the satellite control system will try to keep the satellite Ground systems have the information required to predict this deterministic profile, and, using the beacon beam A desired beacon value A predicted measured beacon value In one embodiment, the beacon value processor Recalling that the correction values Block Block The foregoing may be practiced in two distinct embodiments. In the first embodiment, the beacon values described above are beacon beam values (e.g. the magnitude of each of the beacon beams In another embodiment of the present invention, the effect of quantization errors is reduced by selecting the quantized coefficients based at least in part on an explicit evaluation of the effects of quantization on beam quality. In this embodiment, the concept is to evaluate the effect of quantization with the antenna pattern calculator In block The method above has the advantage of improving performance with relatively little additional real-time processing. More elaborate approaches are also possible—the branch of applied mathematics called “integer programming” is devoted to methods of finding optimal solutions to problems subject to quantization constraints, and any of the methods of integer programming could be applied here, such as “branch and bound” or “cutting plane”. Nominal beamweight coefficients Next, as shown in blocks Turning now to In using the foregoing technique, an “improved” EIRP can be defined as a beam having the highest average EIRP at all of the vertices An iterative technique can be employed wherein, preferably beginning with the vertex A set of nominal beamweight coefficients A perturbed beam is then defined. In one embodiment, the perturbed beam is angularly displaced toward one of the vertices, such as perturbed beam A set of perturbed beamweight coefficients Of course, the foregoing operations need not be limited to examination of a single perturbed beam. The foregoing operations can be repeated for additional vertices (e.g. using perturbed beam The foregoing refers to a generally defined peripheral edge of the nominal beam as having “vertices” and computations are performed to determine the perturbed beam whose quantized coefficients result in the best performance at those vertices. However, although it is convenient to implement the present invention by assuming the beam shapes are hexagonal and the vertices are those disposed at each corner of the hexagon, the shape of the beam need not be a hexagon, nor need the vertices of the beam shape be symmetrically arranged about the periphery of the beam. Instead, the vertices can refer to any portion of the beam at its periphery. As shown in block Beacon and payload beamweight coefficients In this embodiment, one of the inputs to the quantizer In one embodiment, the element gain/phase prediction module The module The measurement residuals are used by the estimate and model corrector The second set of gain/phase predictions In one embodiment, this is accomplished by the element gain/phase prediction module In the illustrated embodiment, two sets of gain and phase predictions are generated. The first set, propagated gain/phase The second set of gain/phase predictions The foregoing data is provided to the beamweight quantizer The operations described in This concludes the description of the preferred embodiments of the present invention. The foregoing description of the preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended. Patent Citations
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